render.py

                if not me_materials or me_materials[material_index] is None: # No materials
                    for i1, i2, i3 in indicies:
                        file.write(',\n\t\t<%d,%d,%d>' % (fv[i1], fv[i2], fv[i3])) # vert count
                else:
                    material = me_materials[material_index]
                    for i1, i2, i3 in indicies:
                        if me.vertex_colors and material.use_vertex_color_paint:
                            # Colour per vertex - vertex colour

                            col1 = cols[i1]
                            col2 = cols[i2]
                            col3 = cols[i3]

                            ci1 = vertCols[col1[0], col1[1], col1[2], material_index][0]
                            ci2 = vertCols[col2[0], col2[1], col2[2], material_index][0]
                            ci3 = vertCols[col3[0], col3[1], col3[2], material_index][0]
                        else:
                            # Colour per material - flat material colour
                            diffuse_color = material.diffuse_color
                            ci1 = ci2 = ci3 = vertCols[diffuse_color[0], diffuse_color[1], diffuse_color[2], f.material_index][0]

                        file.write(',\n\t\t<%d,%d,%d>, %d,%d,%d' % (fv[i1], fv[i2], fv[i3], ci1, ci2, ci3)) # vert count


            file.write('\n\t}\n')

            # normal_indices indicies
            file.write('\tnormal_indices {\n')
            file.write('\t\t%d' % (len(me.faces) + quadCount)) # faces count
            for fi, fv in enumerate(faces_verts):

                if len(fv) == 4:
                    indicies = (0, 1, 2), (0, 2, 3)
                else:
                    indicies = ((0, 1, 2),)

                for i1, i2, i3 in indicies:
                    if f.use_smooth:
                        file.write(',\n\t\t<%d,%d,%d>' %\
                        (uniqueNormals[verts_normals[fv[i1]]][0],\
                         uniqueNormals[verts_normals[fv[i2]]][0],\
                         uniqueNormals[verts_normals[fv[i3]]][0])) # vert count
                    else:
                        idx = uniqueNormals[faces_normals[fi]][0]
                        file.write(',\n\t\t<%d,%d,%d>' % (idx, idx, idx)) # vert count

            file.write('\n\t}\n')

            if uv_layer:
                file.write('\tuv_indices {\n')
                file.write('\t\t%d' % (len(me.faces) + quadCount)) # faces count
                for fi, fv in enumerate(faces_verts):

                    if len(fv) == 4:
                        indicies = (0, 1, 2), (0, 2, 3)
                    else:
                        indicies = ((0, 1, 2),)

                    uv = uv_layer[fi]
                    if len(faces_verts[fi]) == 4:
                        uvs = tuple(uv.uv1), tuple(uv.uv2), tuple(uv.uv3), tuple(uv.uv4)
                    else:
                        uvs = tuple(uv.uv1), tuple(uv.uv2), tuple(uv.uv3)

                    for i1, i2, i3 in indicies:
                        file.write(',\n\t\t<%d,%d,%d>' %\
                        (uniqueUVs[uvs[i1]][0],\
                         uniqueUVs[uvs[i2]][0],\
                         uniqueUVs[uvs[i3]][0]))
                file.write('\n  }\n')

            if me.materials:
                try:
                    material = me.materials[0] # dodgy
                    writeObjectMaterial(material)
                except IndexError:
                    print(me)

            writeMatrix(matrix)
            
            #Importance for radiosity sampling added here: 
            file.write('\tradiosity { importance %3g }\n' % importance) 

            file.write('}\n') # End of mesh block
            file.write('%s\n' % name) # Use named declaration to allow reference e.g. for baking. MR

            bpy.data.meshes.remove(me)

    def exportWorld(world):
        render = scene.render
        camera = scene.camera
        matrix = global_matrix * camera.matrix_world
        if not world:
            return
        #############Maurice#################################### 
        #These lines added to get sky gradient (visible with PNG output)
        if world:
            #For simple flat background:
            if not world.use_sky_blend:
                #Non fully transparent background could premultiply alpha and avoid anti-aliasing display issue: 
                if render.alpha_mode == 'PREMUL' or render.alpha_mode == 'PREMUL' :
                    file.write('background {rgbt<%.3g, %.3g, %.3g, 0.75>}\n' % (tuple(world.horizon_color)))
                #Currently using no alpha with Sky option:
                elif render.alpha_mode == 'SKY':
                    file.write('background {rgbt<%.3g, %.3g, %.3g, 0>}\n' % (tuple(world.horizon_color)))
                #StraightAlpha:
                else:
                    file.write('background {rgbt<%.3g, %.3g, %.3g, 1>}\n' % (tuple(world.horizon_color)))

                    
            worldTexCount=0
            #For Background image textures
            for t in world.texture_slots: #risk to write several sky_spheres but maybe ok.
                worldTexCount+=1
                if t and t.texture.type == 'IMAGE': #and t.use: #No enable checkbox for world textures yet (report it?)
                    image_filename  = path_image(t.texture.image.filepath)
                    if t.texture.image.filepath != image_filename: t.texture.image.filepath = image_filename
                    if image_filename != '' and t.use_map_blend: 
                        texturesBlend = image_filename
                        #colvalue = t.default_value
                        t_blend = t
                    #commented below was an idea to make the Background image oriented as camera taken here: http://news.povray.org/povray.newusers/thread/%3Cweb.4a5cddf4e9c9822ba2f93e20@news.povray.org%3E/
                    #mappingBlend = (" translate <%.4g,%.4g,%.4g> rotate z*degrees(atan((camLocation - camLookAt).x/(camLocation - camLookAt).y)) rotate x*degrees(atan((camLocation - camLookAt).y/(camLocation - camLookAt).z)) rotate y*degrees(atan((camLocation - camLookAt).z/(camLocation - camLookAt).x)) scale <%.4g,%.4g,%.4g>b" % (t_blend.offset.x / 10 ,t_blend.offset.y / 10 ,t_blend.offset.z / 10, t_blend.scale.x ,t_blend.scale.y ,t_blend.scale.z))#replace 4/3 by the ratio of each image found by some custom or existing function
                    #using camera rotation valuesdirectly from blender seems much easier
                    if t_blend.texture_coords=='ANGMAP':
                        mappingBlend = ("")
                    else:
                        mappingBlend = (" translate <%.4g-0.5,%.4g-0.5,%.4g-0.5> rotate<0,0,0>  scale <%.4g,%.4g,%.4g>" % (t_blend.offset.x / 10 ,t_blend.offset.y / 10 ,t_blend.offset.z / 10, t_blend.scale.x*0.85 , t_blend.scale.y*0.85 , t_blend.scale.z*0.85 ))
                        #The initial position and rotation of the pov camera is probably creating the rotation offset should look into it someday but at least background won't rotate with the camera now. 
                    #Putting the map on a plane would not introduce the skysphere distortion and allow for better image scale matching but also some waay to chose depth and size of the plane relative to camera.
                    file.write('sky_sphere {\n')            
                    file.write('\tpigment {\n')
                    file.write("\t\timage_map{%s \"%s\" %s}\n\t}\n\t%s\n" % (imageFormat(texturesBlend),texturesBlend,imgMapBG(t_blend),mappingBlend))
                    file.write('}\n')  
                    #file.write('\t\tscale 2\n')
                    #file.write('\t\ttranslate -1\n')
      
            #For only Background gradient        
        
            if worldTexCount==0:
                if world.use_sky_blend:
                    file.write('sky_sphere {\n')            
                    file.write('\tpigment {\n')
                    file.write('\t\tgradient y\n')#maybe Should follow the advice of POV doc about replacing gradient for skysphere..5.5
                    file.write('\t\tcolor_map {\n')
                    if render.alpha_mode == 'STRAIGHT':
                        file.write('\t\t\t[0.0 rgbt<%.3g, %.3g, %.3g, 1>]\n' % (tuple(world.horizon_color)))
                        file.write('\t\t\t[1.0 rgbt<%.3g, %.3g, %.3g, 1>]\n' % (tuple(world.zenith_color)))
                    elif render.alpha_mode == 'PREMUL':
                        file.write('\t\t\t[0.0 rgbt<%.3g, %.3g, %.3g, 0.99>]\n' % (tuple(world.horizon_color)))
                        file.write('\t\t\t[1.0 rgbt<%.3g, %.3g, %.3g, 0.99>]\n' % (tuple(world.zenith_color))) #aa premult not solved with transmit 1
                    else:
                        file.write('\t\t\t[0.0 rgbt<%.3g, %.3g, %.3g, 0>]\n' % (tuple(world.horizon_color)))
                        file.write('\t\t\t[1.0 rgbt<%.3g, %.3g, %.3g, 0>]\n' % (tuple(world.zenith_color)))
                    file.write('\t\t}\n')
                    file.write('\t}\n')
                    file.write('}\n')
                    #sky_sphere alpha (transmit) is not translating into image alpha the same way as "background"

            if world.light_settings.use_indirect_light:
                scene.pov_radio_enable=1 
                
            #Maybe change the above to scene.pov_radio_enable = world.light_settings.use_indirect_light ?


        ###############################################################

        mist = world.mist_settings

        if mist.use_mist:
            file.write('fog {\n')
            file.write('\tdistance %.6f\n' % mist.depth)
            file.write('\tcolor rgbt<%.3g, %.3g, %.3g, %.3g>\n' % (tuple(world.horizon_color) + (1 - mist.intensity,)))
            #file.write('\tfog_offset %.6f\n' % mist.start)
            #file.write('\tfog_alt 5\n')
            #file.write('\tturbulence 0.2\n')
            #file.write('\tturb_depth 0.3\n')
            file.write('\tfog_type 1\n')
            file.write('}\n')
        if scene.pov_media_enable:
            file.write('media {\n')
            file.write('\tscattering { 1, rgb %.3g}\n' % scene.pov_media_color)
            file.write('\tsamples %.d\n' % scene.pov_media_samples)
            file.write('}\n')

    def exportGlobalSettings(scene):

        file.write('global_settings {\n')
        file.write('\tassumed_gamma 1.0\n')
        file.write('\tmax_trace_level %d\n' % scene.pov_max_trace_level)

        if scene.pov_radio_enable:
            file.write('\tradiosity {\n')
            file.write("\t\tadc_bailout %.4g\n" % scene.pov_radio_adc_bailout)
            file.write("\t\talways_sample %d\n" % scene.pov_radio_always_sample)
            file.write("\t\tbrightness %.4g\n" % scene.pov_radio_brightness)
            file.write("\t\tcount %d\n" % scene.pov_radio_count)
            file.write("\t\terror_bound %.4g\n" % scene.pov_radio_error_bound)
            file.write("\t\tgray_threshold %.4g\n" % scene.pov_radio_gray_threshold)
            file.write("\t\tlow_error_factor %.4g\n" % scene.pov_radio_low_error_factor)
            file.write("\t\tmedia %d\n" % scene.pov_radio_media)
            file.write("\t\tminimum_reuse %.4g\n" % scene.pov_radio_minimum_reuse)
            file.write("\t\tnearest_count %d\n" % scene.pov_radio_nearest_count)
            file.write("\t\tnormal %d\n" % scene.pov_radio_normal)
            file.write("\t\tpretrace_start %.3g\n" % scene.pov_radio_pretrace_start)
            file.write("\t\tpretrace_end %.3g\n" % scene.pov_radio_pretrace_end)
            file.write("\t\trecursion_limit %d\n" % scene.pov_radio_recursion_limit)
            file.write('\t}\n')
        once=1
        for material in bpy.data.materials:
            if material.subsurface_scattering.use and once:
                file.write("\tmm_per_unit %.6f\n" % (material.subsurface_scattering.scale * (-100) + 15))#In pov, the scale has reversed influence compared to blender. these number should correct that
                once=0 #In povray, the scale factor for all subsurface shaders needs to be the same

        if world: 
            file.write("\tambient_light rgb<%.3g, %.3g, %.3g>\n" % tuple(world.ambient_color))

        if material.pov_photons_refraction or material.pov_photons_reflection:
            file.write("\tphotons {\n")
            file.write("\t\tspacing 0.003\n")
            file.write("\t\tmax_trace_level 5\n")
            file.write("\t\tadc_bailout 0.1\n")
            file.write("\t\tgather 30, 150\n")

            
            file.write("\t}\n")

        file.write('}\n')


    # Convert all materials to strings we can access directly per vertex.
    writeMaterial(None) # default material

    for material in bpy.data.materials:
        writeMaterial(material)

    
    #exportMaterials()
    sel = scene.objects
    exportLamps([l for l in sel if l.type == 'LAMP'])
    exportMeta([l for l in sel if l.type == 'META'])
    exportMeshs(scene, sel)
    exportCamera()
    exportWorld(scene.world)
    exportGlobalSettings(scene)

    file.close()
    


def write_pov_ini(filename_ini, filename_pov, filename_image):
    scene = bpy.data.scenes[0]
    render = scene.render

    x = int(render.resolution_x * render.resolution_percentage * 0.01)
    y = int(render.resolution_y * render.resolution_percentage * 0.01)

    file = open(filename_ini, 'w')
    file.write('Input_File_Name="%s"\n' % filename_pov)
    file.write('Output_File_Name="%s"\n' % filename_image)

    file.write('Width=%d\n' % x)
    file.write('Height=%d\n' % y)

    # Needed for border render.
    '''
    file.write('Start_Column=%d\n' % part.x)
    file.write('End_Column=%d\n' % (part.x+part.w))

    file.write('Start_Row=%d\n' % (part.y))
    file.write('End_Row=%d\n' % (part.y+part.h))
    '''

    file.write('Bounding_Method=2\n')#The new automatic BSP is faster in most scenes

    file.write('Display=1\n')#Activated (turn this back off when better live exchange is done between the two programs (see next comment)
    file.write('Pause_When_Done=0\n')
    file.write('Output_File_Type=N\n') # PNG, with POV 3.7, can show background color with alpha. In the long run using the Povray interactive preview like bishop 3D could solve the preview for all formats. 
    #file.write('Output_File_Type=T\n') # TGA, best progressive loading
    file.write('Output_Alpha=1\n')

    if render.use_antialiasing:
        aa_mapping = {'5': 2, '8': 3, '11': 4, '16': 5} # method 2 (recursive) with higher max subdiv forced because no mipmapping in povray needs higher sampling.
        file.write('Antialias=on\n')
        file.write('Sampling_Method=2\n')
        file.write('Antialias_Depth=%d\n' % aa_mapping[render.antialiasing_samples])
        file.write('Antialias_Threshold=0.1\n')#rather high settings but necessary.
        file.write('Jitter=off\n')#prevent animation flicker
 
    else:
        file.write('Antialias=0\n')
    file.write('Version=3.7')
    file.close()


class PovrayRender(bpy.types.RenderEngine):
    bl_idname = 'POVRAY_RENDER'
    bl_label = "Povray 3.7"
    DELAY = 0.05

    def _export(self, scene):
        import tempfile

        self._temp_file_in = tempfile.mktemp(suffix='.pov')
        self._temp_file_out = tempfile.mktemp(suffix='.png')#PNG with POV 3.7, can show the background color with alpha. In the long run using the Povray interactive preview like bishop 3D could solve the preview for all formats.
        #self._temp_file_out = tempfile.mktemp(suffix='.tga')
        self._temp_file_ini = tempfile.mktemp(suffix='.ini')
        '''
        self._temp_file_in = '/test.pov'
        self._temp_file_out = '/test.png'#PNG with POV 3.7, can show the background color with alpha. In the long run using the Povray interactive preview like bishop 3D could solve the preview for all formats.
        #self._temp_file_out = '/test.tga'
        self._temp_file_ini = '/test.ini'
        '''

        def info_callback(txt):
            self.update_stats("", "POVRAY 3.7: " + txt)

        write_pov(self._temp_file_in, scene, info_callback)

    def _render(self):

        try:
            os.remove(self._temp_file_out) # so as not to load the old file
        except OSError:
            pass

        write_pov_ini(self._temp_file_ini, self._temp_file_in, self._temp_file_out)

        print ("***-STARTING-***")

        pov_binary = "povray"
        
        extra_args = []
        
        if sys.platform == 'win32':
            import winreg
            regKey = winreg.OpenKey(winreg.HKEY_CURRENT_USER, 'Software\\POV-Ray\\v3.7\\Windows')

            if bitness == 64:
                pov_binary = winreg.QueryValueEx(regKey, 'Home')[0] + '\\bin\\pvengine64'
            else:
                pov_binary = winreg.QueryValueEx(regKey, 'Home')[0] + '\\bin\\pvengine'
        else:
            # DH - added -d option to prevent render window popup which leads to segfault on linux
            extra_args.append("-d")

        if 1:
            # TODO, when povray isnt found this gives a cryptic error, would be nice to be able to detect if it exists
            try:
                self._process = subprocess.Popen([pov_binary, self._temp_file_ini] + extra_args) # stdout=subprocess.PIPE, stderr=subprocess.PIPE
            except OSError:
                # TODO, report api
                print("POVRAY 3.7: could not execute '%s', possibly povray isn't installed" % pov_binary)
                import traceback
                traceback.print_exc()
                print ("***-DONE-***")
                return False

        else:
            # This works too but means we have to wait until its done
            os.system('%s %s' % (pov_binary, self._temp_file_ini))

        # print ("***-DONE-***")
        return True

    def _cleanup(self):
        for f in (self._temp_file_in, self._temp_file_ini, self._temp_file_out):
            try:
                os.remove(f)
            except OSError:  #was that the proper error type?
                pass

        self.update_stats("", "")

    def render(self, scene):

        self.update_stats("", "POVRAY 3.7: Exporting data from Blender")
        self._export(scene)
        self.update_stats("", "POVRAY 3.7: Parsing File")

        if not self._render():
            self.update_stats("", "POVRAY 3.7: Not found")
            return

        r = scene.render
##WIP output format 
##        if r.file_format == 'OPENEXR':
##            fformat = 'EXR'
##            render.color_mode = 'RGBA'
##        else:
##            fformat = 'TGA'
##            r.file_format = 'TARGA'            
##            r.color_mode = 'RGBA'

        # compute resolution
        x = int(r.resolution_x * r.resolution_percentage * 0.01)
        y = int(r.resolution_y * r.resolution_percentage * 0.01)

        # Wait for the file to be created
        while not os.path.exists(self._temp_file_out):
            # print("***POV WAITING FOR FILE***")
            if self.test_break():
                try:
                    self._process.terminate()
                    print("***POV INTERRUPTED***")
                except OSError:
                    pass
                break
            
            poll_result = self._process.poll()
            if poll_result is not None:
                print("***POV PROCESS FAILED : %s ***" % poll_result)
                self.update_stats("", "POVRAY 3.7: Failed")
                break

            time.sleep(self.DELAY)

        if os.path.exists(self._temp_file_out):
            # print("***POV FILE OK***")
            self.update_stats("", "POVRAY 3.7: Rendering")

            prev_size = -1

            def update_image():
                # print("***POV UPDATING IMAGE***")
                result = self.begin_result(0, 0, x, y)
                lay = result.layers[0]
                # possible the image wont load early on.
                try:
                    lay.load_from_file(self._temp_file_out)
                except SystemError:
                    pass
                self.end_result(result)

            # Update while povray renders
            while True:
                # print("***POV RENDER LOOP***")

                # test if povray exists
                if self._process.poll() is not None:
                    print("***POV PROCESS FINISHED***")
                    update_image()
                    break

                # user exit
                if self.test_break():
                    try:
                        self._process.terminate()
                        print("***POV PROCESS INTERRUPTED***")
                    except OSError:
                        pass

                    break

                # Would be nice to redirect the output
                # stdout_value, stderr_value = self._process.communicate() # locks


                # check if the file updated
                new_size = os.path.getsize(self._temp_file_out)

                if new_size != prev_size:
                    update_image()
                    prev_size = new_size

                time.sleep(self.DELAY)
        else:
            print("***POV FILE NOT FOUND***")
        
        print("***POV FINISHED***")
        self._cleanup()